Most piston operated engines, for example, use chain driven camshafts to control the actuation of spring-loaded intake and exhaust valves. Other engines have used slide valves that are actuated by complex gearing. All such systems are fairly complex, and have high friction losses that reduce engine efficiency. Such systems also wear out rapidly, and thus are expensive to maintain. It therefore would be highly desirable to provide an expansible chamber device having intake and exhaust valves that either are condition responsive, or are actuated by contact with the working member of the engine. In this manner, all mechanical linkages such as camshafts and the like are eliminated to minimize weight, complexity and wear, and to increase engine efficiency.
Various systems have been proposed for eliminating the use of mechanical linkages to control the intake and/or exhaust valve functions in expansible chamber devices. See U.S. Pat. Nos. 1,527,678, 3,910,160, 4,050,357 and 4,283,995. However none of the systems of which applicant is aware provide any means to change or adjust the event of valve closing while the engine is in operation, and some are quite complex and are likely to be unreliable in operation over extended periods of time.
Accordingly, there has been a long felt need for a reliable and efficient valve system for regulating the flow of fluid into and out of the chamber of a cyclically operable expansible chamber device such as an engine, compressor, pump, expander, blender and metering system, to name but a few of the applications in which the present invention is usable. Such valve systems should be constructed and arranged so that there is a flexible relationship between cycle phase and valve operation, particularly since operation naturally produces cycles of fluid pressures and flows that have characteristic properties which can be used to operate valves in an efficient manner. Applicant has recognized that, for example, a series combination of two check valves which are oriented to permit free flow away from each other, can be controllably restrained in the open position so as to perform most, if not all, of the inlet and/or outlet functions required of cyclically operable expansible chamber applications. Such a valve system will not normally open between two zones having significantly different fluid pressures, so that dissipation of fluid energy from such event is avoided. On the other hand the valve system will open when pressures across it are reversed, which will usually happen twice during the typical cycle: once on rising chamber pressure and once on falling chamber pressure. The valve will remain open until the closing forces generated by the flow of working fluid through the upstream valve exceeds the forces that restrain the valve from closing. Applicant has also recognized that the magnitude of the restraining force can be controlled, and can be set or timed to allow any amount of flow of working medium that is desired in a particular application. Such a valve system can therefore be actuated at the most efficient points in the pressure cycle with a minimum of control energy requirement.
A broad object of the present invention is to provide an expansible chamber device having a unique intake valve system that closes in response to a working medium flow characteristic, such as flow velocity, and which is subject to variable restraining forces to provide control over valve closing.
Another object of the present invention is to provide a motor of the type described having an intake valve that is closed automatically in response to a characteristic of intake flow, such as its rate or velocity, said valve being held open by a restraining force that is variable to provide control.
Another object of the present invention is to provide a new and improved motor of the type described having a restrained intake valve that closes automatically in response to the velocity of flow of working fluid, and means for changing or adjusting the restraining force in order to set the particular flow velocity at which the valve can close.
Another object of the present invention is to provide an expansible chamber motor having a new and improved exhaust valve system that automatically opens at low pressure differential between cylinder pressure and ambient pressure, and which is closed in response to direct or indirect impingement of the movable member.
A further object of the present invention is to provide a new and improved process for regulating the flow of a working medium from one chamber to another by providing a variable restraining force that controls the operation of a check valve between the chambers.